Mercury Evidence of Intense Volcanism Preceded Oceanic Anoxic Event 1d
Hanwei Yao, Xi Chen, Runsheng Yin, Stephen E. Grasby, Helmut Weissert, Xue Gu, Chengshan Wang
Abstract
Abstract Geochemical studies of marine sediments indicate that most Oceanic Anoxic Events (OAEs) appear coincident with Large Igneous Province (LIP) volcanism. OAE 1d records peculiar paleoceanographic changes and global carbon cycle perturbations, however, its association with volcanism has not yet been supported by robust geochemical evidence. To examine the potential role of volcanism we investigated the mercury (Hg) concentration and isotopic record of OAE 1d interval at the Youxia section, southern Tibet. The interval prior to OAE 1d is marked by a combined positive Δ 199 Hg and Hg content shift, which suggests a volcanic Hg source. These findings are consistence with a prominent increase in sea surface temperatures and atmospheric CO 2 before OAE 1d. We suggest that eruption of the central portion of the Kerguelen LIP may have been the main source of the Hg anomaly and resulted in global environment perturbations that drove the onset of the anoxia event.